Improvement in steam-generators



'rarasL PATENT QFFICE.

THOMAS MITCHELL, OF ALBANY, NEV YORK.

IMPROVEMENT IN STEAM-GENERATORS.

y Specification forming part of Letters Patent No. 59.051, dated October 33, 1866.

To all whom t may concern:

Be it known that I, THoaIAs MITCHELL, of Albany, in the county of Albany and State of New York, have invented a new and Improved Machine for Generating Steam, to take the place of steam-boilers; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the annexed drawings, making a part ofthis specification.

Figure 1 is an outside view of the steamchamber. Fig. 2 is the water-tank. Fig. 3 is the pressure-valve.

Similar letters of reference indicate corresponding parts in the several figures.

This invention consists in the use of a steam tank or chamber, a water tank, a pressurevalve, a force-pump, connecting-pipes, valves, cocks, expansion-rods, and damper-doors, so made and connected that water is let into the steam-chamber when heated to the degree required, so that any given number of pounds of steam may be made instantaneous, and the quantity of water let in and graduated by the pressure of steam in the chamber.

This invention secures three important advantages in regard to steam power-rst, perfect safety against boiler-explosions; second, a saving of at least one-half the amount of fuel; and, thirdly, about three -fourths of the bulk, weight, and cost of steam-boilers, substantially as hereinafter described.

Letter A of Fig. l is a flue, on top of which the smoke-stack is placed, answering the purposes of a brace for the head and crown-sheet of the chamber, increasing the steam-surface, and a draft from the furnace.

Letter B is a water-distributer, made guttering and with an inclination downward from the ue, receiving the water from the pipe C, conducting a part of it to the walls of the chamber, and letting a part fall from the short gutters midway on the crown-sheet below.

Letters D D are dampcrdoors, which serve the purposes of covering the draftopenings when down and shutting off the draft from the center flue when up, and also the all-important one of covering and protecting the crown-sheet from being heated too hot. These doors are moved by the expansion-rods G G, one end of each of which is fastened firmly in each side of the chamber, and the other loose, so that when the degree of heat under the crownsheet is obtained sufficiently high to evap- "orate the water let into the chamber immediately into the steam, and yet not so high as to injurethe crown-sheet, at exactly this point these rods have expanded to such a length thatthey raise the dam pers covering thc crownsheet, and also covering completely the Hue, shutting off the draft from the chimney, and opening the doors in the sides of the chamber, giving a clear space for thc cold air to pass through.

E is the lever (and which may be doubled to give a quicker motion) by which the doors are moved by the expansion-rods.

Fig. 2 is the water-tank, letter A of which is the pipe leading from a force-pum p, through which the water is forced into the tank, keeping up a pressure in it high enough to feed the chamber against any given pressure of steam. Letter B is t-he cock on the connectingpipe between the water-tank and the steamchamber, on which is a gear-wheel, and moved by the gear-rack, connected with the lever G. This lever may also be doubled to give a quick motion to the cock.

Fig. 3 is the pressure-valve. Letters A A is the pipe leading from the steam-chamber into it, and thus always keeping the pressure in the valve and the chamber equal. There is rubber packing fastened between two flanges,

represented by the one under the dome on this valve, the full size of the dan ge separating the steam below thelange from the clear space above it under the dome. B is the stern rising up through the center of the valve, on the lower end of which is a hat washer, resting on the top of the packing. O is a lever resting on the top of this stem or fulcrum. On the upper end of this lever is the gear-rack already described.

It is clear vfrom this that, the pressure being equal in the chamber and in this valve, the stem will rise and fall by the steams rising or falling, when it falls, which it will do,l by exhausting any amount of steam from the chamber, and this fall will let the lever O fall also, which turns the cock on thc connectingpipe between the steam-chamber and the water-tank, and therefore turning the cock, and thus letting just water enough into the chamber, which is instantaneously evaporated into 'placed, giving the pressure required to feed steam to make up the quantity of steam thus exhausted, and which again instantly raises the stem in the pressure'valve, and thus again shutting ott' the water from the tank, and keeping it shut oi' until more steam is used by the ruiming of the engine or otherwise; and this action is continued as long as the lire is kept up in'the furnace and the force-pump is kept in motion.

Letter D of Fig. 2 is a water-valve for the purpose of letting the water oft Wh en the pressure is greater than requisite to feed the steamchamber, and which is again conducted back into the reservoir by the pipe E E, if required, for further use.

LetterF is the beam, containing figures and niches, on any one of which the pea may befd thechamber against any given number ot' pounds of steam. If sixty pounds is wanted, then set the pea on sixty-five pounds on the water-valve and sixty on the beam connected with the pressure-valve. In the same manner they are to be set to give any n uinber of pounds of steam required.

The mode of operation is as follows: First,

This is continued until the amount of steam required is obtained.' When this is done, the pump is again attached to the engine, and the steam being let onto it, as in ordinary cases, continues the action as long as is required.

It will be seen by this invention that it is impossible for either Water to accumulate in the chamber, or the crown-sheet be injured by any amount of fire it is possible to make in Patent, is-

The combination ofthe lneans, substantially as herein described, for generati ng the steam, with the means, substantially as herein described, for controlling the introduction of the water into the generator by the pressure of steam generated, as and for the purpose set re is made in the fire-box, when there is no forth.

water in the steam-chamber, until the heat reaches that degree under the crown-sheet which lifts the damper-doors, -at which point water is forced by hand with the force-pump, (detaching it from the engine for this purpose.)

Tues. MITCHELL. 

